Vincent Bossilkov was born to a family of Bulgarian Latin Rite Catholics on November 16, 1900, in Belene, Bulgaria.

In 1927 he went to Rome to take his doctorate at the Pontifical Oriental Institute, where he wrote a thesis on the Union of Bulgarians with the Holy See during the early 13th century.

[3] In the wake of World War II, the Soviet Union invaded the Kingdom of Bulgaria and installed a Communist government answering to Joseph Stalin.

In the same year the government deported the Apostolic Delegate, seized Catholic Church property, and suppressed the religious congregations.

[4][5] Bossilkov suffered both physical and mental torture in prison, where he was told to confess to being the leader of a Catholic conspiracy to subvert Communism.

[6] At a political "show trial", two guns supposedly seized from the Catholic college in Sophia were presented as evidence.

The accused convoked a diocesan council in which it was decided to combat Communism through religious conferences, held in Bulgaria, activities called ' a mission.'

Pope Pius XII had mentioned Bossilkov's being condemned to death in his encyclical letter "Orientales Ecclesias" to the Oriental Churches in 1952.